1. Field of the Invention
The present invention generally relates to a snap fastener composed of a socket element and a stud element adapted to be coupled together, and more particularly to a socket element assembly including a socket member and a capped eyelet adapted to be joined together to attach the socket element assembly to a garment fabric or the like.
2. Prior Art
Japanese Utility Model Laid-open Publication No. 57-85910 discloses, as reillustrated in FIG. 5, a socket element assembly for snap fasteners which includes a locking means for holding a capped eyelet A in interlocking engagement with a garment fabric B against rotation. The locking means comprises a plurality of prongs C, C projecting from a fabric-engaging flange of the eyelet A. Prior to attachment of a socket member D to the garment fabric by means of the eyelet A, the eyelet A itself is fastened to the garment fabric B by driving the prongs C through the garment fabric B and then bending projecting ends of the respective prongs C. With the locking prongs C thus clinched, the garment fabric B becomes wavy or wrinkled around the eyelet A so that a garment to which the socket element assembly is attached becomes unsightly. The socket element assembly having such prongs C has a relatively large thickness and hence it is likely to be damaged by laundering.
Low profile socket element assemblies are known, however, they normally have a drawback in that a capped eyelet is market with scars on the outer surface of a cap when the eyelet is axially compressed to join with a socket member.
U.S. Pat. No. 3,333,306 discloses, as reillustrated here in FIG. 6, a socket element assembly wherein an eyelet E has a pair of reinforcing wings F, F punches from a flange of the eyelet E and folded over to project radially inwardly in a space between the cap G and the flange. The reinforcing wings F, F coact with a wall of the tubular shank to absorb the riveting force applied thereto when the eyelet is joined with a socket member H. With this construction, since the wings F, F can absorb only incompletely the riveting force applied thereto, it is impossible to prevent the cap G from being marked with a scar in its outer surface. With the wings F, F disposed between the cap G and the flange, the socket element assembly has a low profile. This low profile socket element assembly howevere is not provided with any means for preventing relative rotation between the eyelet E, more particularly the cap G thereof and the garment fabric I. To prevent such relative rotation, it is necessary to firmly grip the garment fabric I at a portion thereof adjacent to the tubular shank where the capped eyelet E and the socket member H are joined together. The garment fabric portion thus gripped is likely to be damaged due to stresses concentrated thereon.
As shown in FIGS. 5 and 6, each of the socket members D, H of the prior socket element assemblies includes a one-piece socket body of metal formed by press working. In assembling the socket member, the outer edge of a cup-like socket member is bent or drawn radially inwardly to retain a snap ring which has been inserted in the socket member. In this instance, care must be taken to draw the outer edge while keeping a large clearance between the snap ring and the socket member to allow displacement of the snap ring within the socket member. With such drawing operation, it is difficult to produce socket members of a low profile and uniform quality.